Magnetic Nanospheres Encapsulated by Mesoporous Copper Oxide Shell for Selective Isolation of Hemoglobin

A novel strategy for the preparation of magnetic nanospheres encapsulated by mesoporous copper oxide shell, shortly termed as Fe 3 O 4 @mCuO, is reported via the calcination of Cu(NH 3 ) 4 (NO 3 ) 2 into continuous mesoporous CuO shell onto the surface of Fe 3 O 4 nanoparticles. The magnetic nanospheres are characterized to possess stable core–shell structure with a crystalline mesoporous CuO layer, exhibiting a CuO loading content of 25.2 ± 1.1% along with a favorable magnetic susceptibility. Fe 3 O 4 @mCuO nanospheres exhibit favorable selectivity on the adsorption of hemoglobin with a high adsorption capacity of up to 1162.5 mg g –1 . After adsorption, the high magnetic susceptibility allows convenient separation of the nanospheres by an external magnet. The retained hemoglobin could be readily recovered by using 0.5% (m/v) sodium dodecyl sulfate (SDS) as stripping reagent, providing a recovery of 78%. Circular dichroism spectra illustrate virtually no change in the conformation of hemoglobin after the process of adsorption/desorption. Fe 3 O 4 @mCuO nanospheres are further applied for the selective isolation of hemoglobin from human whole blood, achieving high-purity hemoglobin as demonstrated by SDS-PAGE (polyacrylamide gel electrophoresis) assays.